Found in Southeast and South Asia, five Chrysopelea snake species have been observed twisting their ribs and flattening their bodies in midair, but this doesn't fully explain how the reptiles control their descent.

"Other snakes flatten their bodies as well," said Jake Socha, a biologist at Virginia Tech. For example, king cobras can flatten their hoods for defensive purposes.

To find out what else enables the snakes to glide, Socha and his colleagues used four cameras to record four flying snakes as they leaped off a five-story tower to another, smaller tower several dozen yards away.

The team then used the images to create 3-D computer models of the reptiles' body positions during flight. (See snake pictures.)

The images and models revealed that the snakes position their bodies at 25-degree angles as they fall—heads up, tails down.

The effect is similar to what happens when you stick your arm out of a moving car and rotate your hand so the palm is pointed slightly upward.

"You hand is now angled to the oncoming flow, and that angle helps push the air down," Socha said. "As a consequence, your hand goes up."

The Chrysopelea snakes, which can grow up to 4 feet (1.2 meters) long, also hold their bodies in S-shaped configurations while gliding. The computer model suggested this twisty position helps them stay aloft. Subsequent experiments proved the software right.

The team tested the aereodynamics of different snake shapes using plastic models in a water tunnel.